Apparatus for controlling temperature uniformity of a showerhead

ABSTRACT

An apparatus for controlling thermal uniformity of a substrate-facing surface of a showerhead is provided herein. In some embodiments, the thermal uniformity of the substrate facing surface of the showerhead may be controlled to be more uniform. In some embodiments, the thermal uniformity of the substrate facing surface of the showerhead may be controlled to be non-uniform in a desired pattern. In some embodiments, an apparatus for controlling thermal uniformity of a substrate-facing surface of a showerhead may include a showerhead having a substrate facing surface and one or more plenums for providing one or more process gases through a plurality of gas distribution holes formed through the substrate facing surface of the showerhead; and a plurality of flow paths having a substantially equivalent fluid conductance disposed within the showerhead to flow a heat transfer fluid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent applicationSer. No. 61/298,676, filed Jan. 27, 2010, which is herein incorporatedby reference.

FIELD

Embodiments of the present invention generally relate to apparatus forsubstrate processing.

BACKGROUND

In many conventional substrate processes, cooling channels may beprovided in a gas distribution apparatus, or showerhead, to facilitatecooling a processing volume-facing faceplate of the showerhead duringprocessing to maintain a desired temperature profile on the faceplate.The cooling channels are typically configured to facilitate providing adesired temperature profile of the showerhead faceplate during substrateprocessing.

The inventors have provided an improved apparatus for controlling thetemperature profile of a faceplate of a showerhead.

SUMMARY

An apparatus for controlling thermal uniformity of a substrate-facingsurface of a showerhead is provided herein. In some embodiments, thethermal uniformity of the substrate facing surface of the showerhead maybe controlled to be more uniform. In some embodiments, the thermaluniformity of the substrate facing surface of the showerhead may becontrolled to be non-uniform in a desired pattern. In some embodiments,an apparatus for controlling thermal uniformity of a substrate-facingsurface of a showerhead may include a showerhead having a substratefacing surface and one or more plenums for providing one or more processgases through a plurality of gas distribution holes formed through thesubstrate facing surface of the showerhead; and a plurality of flowpaths having a substantially equivalent fluid conductance disposedwithin the showerhead to flow a heat transfer fluid.

In some embodiments, an apparatus for controlling thermal uniformity ofa substrate-facing surface of a showerhead may include a showerheadhaving a substrate facing surface and one or more plenums for providingone or more process gases through a plurality of gas distribution holesformed through the substrate facing surface of the showerhead; and aflow path disposed within the showerhead and having an inlet and anoutlet to flow a heat transfer fluid through the flow path, wherein theflow path comprises a first portion and a second portion, each portionhaving a substantially equivalent axial length, wherein the firstportion is spaced about 2 mm to about 10 mm from the second portion, andwherein the first portion provides a flow of heat transfer fluid in adirection opposite a flow of heat transfer fluid of the second portion.

In some embodiments, an apparatus for controlling thermal uniformity ofa substrate-facing surface of a showerhead may include a showerheadhaving a substrate facing surface and one or more plenums for providingone or more process gases through a plurality of gas distribution holesformed through the substrate facing surface of the showerhead; and afirst flow path and a second flow path disposed within the showerhead,each having an inlet and an outlet to flow a heat transfer fluid throughthe respective flow path, wherein each flow path has a substantiallyequivalent axial length, and wherein the first flow path and the secondflow path a inversely symmetrical about an axis that passes through acentral axis of the showerhead.

The above summary is provided to briefly discuss some aspects of thepresent invention and is not intended to be limiting of the scope of theinvention. Other embodiments and variations of the invention areprovided below in the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention, briefly summarized above anddiscussed in greater detail below, can be understood by reference to theillustrative embodiments of the invention depicted in the appendeddrawings. It is to be noted, however, that the appended drawingsillustrate only typical embodiments of this invention and are thereforenot to be considered limiting of its scope, for the invention may admitto other equally effective embodiments.

FIG. 1 depicts a process chamber having a showerhead in accordance withsome embodiments of the present invention.

FIG. 1A depicts a cross-sectional side view of a showerhead inaccordance with some embodiments of the present invention.

FIGS. 2-6 depict partial cross sectional top views of a showerhead inaccordance with some embodiments of the present invention.

FIG. 7 depicts a heat transfer fluid flow path of a showerhead inaccordance with some embodiments of the present invention.

FIG. 8 depicts a partial cross sectional top view of a showerhead inaccordance with some embodiments of the present invention.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. The figures are not drawn to scale and may be simplifiedfor clarity. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

The inventors have observed that conventional showerheads may haveundesirable temperature profiles, which may lead to undesirable processresults. Embodiments of the present invention provide apparatus forcontrolling the temperature of a showerhead during processing. Theapparatus may control the thermal uniformity of the showerhead duringprocessing. In some embodiments, the thermal uniformity of theshowerhead may be controlled to be more uniform. In some embodiments,the thermal uniformity of the showerhead may be controlled to benon-uniform in a desired pattern. In some embodiments, the inventiveapparatus may advantageously provide one or more flow paths whichprovide a counter flow of heat transfer fluid, thereby facilitatingcontrol of a temperature profile across a faceplate of a showerhead. Inaddition, in some embodiments, the inventive apparatus mayadvantageously provide a showerhead having a plurality of flow pathswhich provide an increased flow rate of heat transfer fluid, therebyfacilitating control of temperature across a faceplate of theshowerhead.

FIG. 1 depicts a process chamber 100 suitable for use in connection withan apparatus for controlling temperature uniformity of a showerhead inaccordance with some embodiments of the present invention. Exemplaryprocess chambers may include the DPS®, ENABLER®, SIGMA™, ADVANTEDGE™, orother process chambers, available from Applied Materials, Inc. of SantaClara, Calif. It is contemplated that other suitable chambers includeany chambers that use showerheads to perform substrate fabricationprocesses.

In some embodiments, the process chamber 100 generally comprises achamber body 102 defining an inner processing volume 104 and an exhaustvolume 106. The inner processing volume 104 may be defined, for example,between a substrate support 108 disposed within the process chamber 100for supporting a substrate 110 thereupon during processing and one ormore gas inlets, such as a showerhead 114 and/or nozzles provided atdesired locations. The exhaust volume may be defined, for example,between the substrate support 108 and a bottom of the process chamber102.

The substrate support 108 generally comprises a body 143 having asubstrate support surface 141 for supporting a substrate 110 thereon. Insome embodiments, the substrate support 108 may include a mechanism thatretains or supports the substrate 110 on the surface of the substratesupport 108, such as an electrostatic chuck, a vacuum chuck, a substrateretaining clamp, or the like (not shown).

In some embodiments, the substrate support 108 may include a radiofrequency (RF) bias electrode 168. The RF bias electrode may be coupledto one or more RF bias power sources through one or more respectivematching networks (one RF bias power source 148A and one matchingnetwork 146A shown in FIG. 1). The one or more bias power sources may becapable of producing up to 12000 W at a frequency of about 2 MHz, orabout 13.56 MHz, or about 60 MHz. In some embodiments, two bias powersources may be provided for coupling RF power through respectivematching networks to the RF bias electrode at a frequency of about 2 MHzand about 13.56 MHz. In some embodiments, three bias power sources maybe provided for coupling RF power through respective matching networksto the RF bias electrode at a frequency of about 2 MHz, about 13.56 MHz,and about 60 MHz. The at least one bias power source may provide eithercontinuous or pulsed power. In some embodiments, the bias power sourcemay be a DC or pulsed DC source.

In some embodiments, the substrate support 108 may include one or moremechanisms for controlling the temperature of the substrate supportsurface 141 and the substrate 110 disposed thereon. For example, one ormore channels (not shown) may be provided to define one or more flowpaths beneath the substrate support surface to flow a heat transferfluid similar to as described below with respect to the showerhead 114.Additional details of apparatus for controlling the temperature of thesubstrate support may be found in U.S. Patent Application 61/298,671,filed Jan. 27, 2010 by K. Bera, et al., and entitled, “APPARATUS FORCONTROLLING TEMPERATURE UNIFORMITY OF A SUBSTRATE,” which is herebyincorporated by reference in its entirety.

The one or more gas inlets (e.g., the showerhead 114) may be coupled toa gas supply 116 for providing one or more process gases into theprocessing volume 104 of the process chamber 100. Although a showerhead114 is shown, additional gas inlets may be provided such as nozzles orinlets disposed in the ceiling or on the sidewalls of the processchamber 100 or at other locations suitable for providing gases asdesired to the process chamber 100, such as the base of the processchamber, the periphery of the substrate support, or the like.

In some embodiments, one or more RF plasma power sources (one RF plasmapower source 148B shown) may be coupled to the process chamber 102through one or more matching networks 146B for providing power forprocessing. In some embodiments, the apparatus 100 may utilizecapacitively coupled RF power provided to an upper electrode proximatean upper portion of the process chamber 102. The upper electrode may bea conductor in an upper portion of the process chamber 102 or formed, atleast in part, by one or more of the ceiling 142, the showerhead 114, orthe like, fabricated from a suitable conductive material. For example,in some embodiments, the one or more RF plasma power sources 148B may becoupled to a conductive portion of the ceiling 142 of the processchamber 102 or to a conductive portion of the showerhead 114. Theceiling 142 may be substantially flat, although other types of ceilings,such as dome-shaped ceilings or the like, may also be utilized. The oneor more plasma sources may be capable of producing up to 5000 W at afrequency of about 2 MHz and/or about 13.56 MHz, or higher frequency,such as 27 MHz and/or 60 MHz and/or 162 MHz. In some embodiments, two RFpower sources may be coupled to the upper electrode through respectivematching networks for providing RF power at frequencies of about 2 MHzand about 13.56 MHz. Alternatively, the one or more RF power sources maybe coupled to inductive coil elements (not shown) disposed proximate theceiling of the process chamber 102 to form a plasma with inductivelycoupled RF power.

In some embodiments, the inner process volume 104 may be fluidly coupledto the exhaust system 120. The exhaust system 120 may facilitate uniformflow of the exhaust gases from the inner process volume 104 of theprocess chamber 102. The exhaust system 120 generally includes a pumpingplenum 124 and a plurality of conduits (not shown) that couple thepumping plenum 124 to the inner process volume 104 of the processchamber 102. Each conduit has an inlet 122 coupled to the inner processvolume 104 (or, in some embodiments, the exhaust volume 106) and anoutlet (not shown) fluidly coupled to the pumping plenum 124. Forexample, each conduit may have an inlet 122 disposed in a lower regionof a sidewall or a floor of the process chamber 102. In someembodiments, the inlets are substantially equidistantly spaced from eachother.

A vacuum pump 128 may be coupled to the pumping plenum 124 via a pumpingport 126 for pumping out the exhaust gases from the process chamber 102.The vacuum pump 128 may be fluidly coupled to an exhaust outlet 132 forrouting the exhaust as required to appropriate exhaust handlingequipment. A valve 130 (such as a gate valve, or the like) may bedisposed in the pumping plenum 124 to facilitate control of the flowrate of the exhaust gases in combination with the operation of thevacuum pump 128. Although a z-motion gate valve is shown, any suitable,process compatible valve for controlling the flow of the exhaust may beutilized.

In operation, the substrate 110 may enter the process chamber 100 via anopening 112 in the chamber body 102. The opening 112 may be selectivelysealed via a slit valve 118, or other mechanism for selectivelyproviding access to the interior of the chamber through the opening 112.The substrate support 108 may be coupled to a lift mechanism 134 thatmay control the position of the substrate support 108 between a lowerposition (as shown) suitable for transferring substrates into and out ofthe chamber via the opening 112 and a selectable upper position suitablefor processing. The process position may be selected to maximize processuniformity for a particular process step. When in at least one of theelevated processing positions, the substrate support 108 may be disposedabove the opening 112 to provide a symmetrical processing region. Afterthe substrate 110 is disposed within the process chamber 102, thechamber may be pumped down to a pressure suitable for forming a plasmaand one or more process gases may be introduced into the chamber via theshowerhead 114 (and/or other gas inlets). RF power may be provided tostrike and maintain a plasma from the process gases to process thesubstrate.

During processing, such as in the above example, the temperature of theshowerhead 114 may be controlled to provide a more uniform temperatureprofile across a substrate-facing surface of the showerhead 114. Forexample, FIG. 1A depicts a cross-sectional side view of a showerhead inaccordance with some embodiments of the present invention. Theshowerhead 114 generally includes one or more plenums 150 coupled via aplurality of conduits 152 to a plurality of gas distribution holes 154for providing process gases to the process chamber in a desired pattern.The plenums 150 may be arranged in zones and may be coupled to the gassupply 116 to provide one or more process gases to the plenums 150.

In some embodiments, the plenums 150 may be disposed between a firstplate 156 and a second plate 158. The plenums may be formed in eitherplate or partially in both plates. In the embodiments depicted in FIG.1A, the plenums 150 are formed by recesses in the second plate 158 withthe first plate 156 providing a cap which covers the recesses to definethe plenums 150. In some embodiments, the width between the plenums 150,or the contact width contact width (e.g., 170 in FIG. 1A) between thefirst plate 156 and the second plate 158, may be between about 0.4inches to about 4.0 inches. The contact width between the first andsecond plates 156, 158 may vary among the different contact locations(such as the center, middle, and edge as depicted in FIG. 1A) as desiredto provide additional control over the rate and/or pattern of thermaltransfer between the first and second plates 156, 158.

In some embodiments, the substrate facing side of the showerhead 114 maybe provided by a substrate facing surface of a third plate (orfaceplate) 160 bonded via a bond layer 162 to the second plate 158. Thefaceplate 160 includes a plurality of holes 154 having a size andgeometry to provide the process gases from the plenum into the chamberin a desired volume and pattern. In some embodiments, a recess 164 maybe provided in the substrate-facing side of the second plate 158 (oralternatively in the faceplate 160, or partially in both the body andthe faceplate) to couple a plurality of the plurality of holes 154 to asingle one or more of the conduits 152. In some embodiments, the thirdplate 160 may be fabricated from silicon carbide.

The showerhead 114 may include one or more mechanisms for controllingthe temperature of the showerhead 114. For example, in some embodiments,one or more heaters may be disposed proximate the showerhead 114 tofurther facilitate control over the temperature of the faceplate 160 ofthe showerhead 114. In some embodiments, the second plate 158 mayinclude one or more heater elements 166. The heater elements 166 mayhave a desired size and pattern to provide heat to the showerhead whendesired to maintain a desired temperature and/or thermal profile acrossthe substrate-facing surface of the showerhead 114, such as across thefaceplate 160. As shown in FIG. 1A, two concentric, annular heaterelements 166 are shown, although other numbers and configurations may beused.

The heaters may be any type of heater suitable to provide control overthe temperature profile of the substrate-facing surface of theshowerhead 114. For example, the heater may be one or more resistiveheaters. In some embodiments the heaters may be disposed below theplenums 150 (e.g., between the plenums 150 and the substrate facingsurface of the showerhead 114, or the faceplate 160). The number andarrangement of the one or more heaters may be varied to provideadditional control over the temperature profile of the substrate-facingsurface of the showerhead 114. For example, in embodiments where morethan one heater is utilized, the heaters may be arranged in a pluralityof zones to facilitate control over the temperature across thesubstrate-facing surface of the showerhead 114, thus providing increasedtemperature control.

In addition, in some embodiments, one or more channels 140 may beprovided, for example in the first plate 156, to define one or more flowpaths (described more fully below with respect to FIGS. 2-8) to flow aheat transfer fluid therethrough. The heat transfer fluid may compriseany fluid suitable to provide adequate transfer of heat to or from theshowerhead 114. For example, the heat transfer fluid may be a gas, suchas helium (He), oxygen (O₂), or the like, or a liquid, such as water,antifreeze, or an alcohol, for example, glycerol, ethylene glycerol,propylene, methanol, or refrigerant fluid such as FREON® (e.g., achlorofluorocarbon or hydrochlorofluorocarbon refrigerant), ammonia orthe like.

A heat transfer fluid source 136 may be coupled to the channels 140 toprovide the heat transfer fluid to the one or more channels 140. Theheat transfer fluid source 136 may comprise a temperature controldevice, for example a chiller or heater, to control the temperature ofthe heat transfer fluid. One or more valves 139 (or other flow controldevices) may be provided between the heat transfer fluid source 136 andthe one or more channels 140 to independently control a rate of flow ofthe heat transfer fluid to each of the one or more channels 140. Acontroller 137 may control the operation of the one or more valves 139and/or of the heat transfer fluid source 136.

The one or more channels 140 may be formed within the showerhead 114, orthe first plate 156, via any means suitable to form the one or morechannels 140 having dimensions adequate to flow a heat transfer fluidtherethrough. For example, in some embodiments, at least a portion ofthe one or more channels 140 may be partially machined into one or bothof a separable top portion 155 and bottom portion 157 of the first plate156. Alternatively, the one or more channels 140 may be fully machinedinto one of the top portion or bottom portion of the first plate 156. Insuch embodiments, the other portion may provide a cap of the channels140 or an insert may be disposed in a portion of each channel 140 toprovide a cap. In some embodiments, the one or more channels 140comprise a plurality of channels having substantially equivalent fluidconductance and residence time. In some embodiments, other features maybe included in the one or more channels 140 to improve heat transferbetween the heat transfer fluid and the substrate facing surface 114.For example, one or more fins 168 may be included within each of the oneor more channels 140 extending partially or wholly across the one ormore channels 140. The fin 168 may provide an increased surface areaavailable for heat transfer, thereby enhancing the heat transfer betweenthe heat transfer fluid flowing through the one or more channels 140 andthe showerhead 114.

The one or more channels 140 may be configured in any manner suitable toprovide adequate control over temperature profile across thesubstrate-facing surface of the showerhead 114 during use. For example,in some embodiments and as depicted in FIG. 2, one channel 140 may beformed within the showerhead 114 defining a single flow path 202 havinga counter flow configuration. An inlet 206 may be coupled to a first end205 of the flow path 202 and an outlet 204 coupled to a second end 207of the flow path 202, thus facilitating a flow of heat transfer fluidfrom the inlet 206 to the outlet 204. The inlet 206 may be coupled to aheat transfer fluid source to provide the heat transfer fluid, asdescribed above with respect to FIG. 1. The channel 140 (e.g., flow path202) may be routed around objects in the showerhead, such as gas linesto the plenums 140, or the like.

In embodiments where the one or more channels 140 define a single flowpath 202, the flow path 202 may comprise a first portion 210 fluidlycoupled to a second portion 212 via a loop or coupling 208. In suchembodiments, the first portion 210 and second portion 212 each have asubstantially equivalent axial length. The axial length is defined asthe axial distance between the inlet 206 and the loop 208 for the firstportion 210, and the distance between the loop 208 and the outlet 204for the second portion 212. The first portion 210 and second portion 212may be disposed proximate one another to facilitate a heat transferbetween the first portion 210 and second portion 212. For example, thedistance between the first portion 210 and second portion 212 may beabout 2 mm to about 30 mm, or between about 2 mm to about 10 mm. In suchembodiments, the first portion 210 and second portion 212 are configuredto provide a counter flow (flow in opposite direction) of heat transferfluid having different temperatures, allowing for a heat transfer from ahotter portion of the heat transfer fluid to a cooler portion of theheat transfer fluid, thus improving temperature uniformity between thefirst portion 210 and second portion 212 at equivalent positions alongthe respective portions. In some embodiments, the inlet 206 and theoutlet 204 may be disposed proximate each other and the first and secondportions 210, 212 of the flow path 202 may together generally windradially inward toward a center point 214 of the substrate support 108then loop back and generally wind radially outward until the end of thefirst and second portions 210, 212 is reached at the loop or coupling208. The inward and outward winding of the first and second portions210, 212 may be interleaved. With the inlet and the outlet near center,the flow path can first wind outward towards the periphery, then windinward towards the center. Such a configuration advantageously providesa flow path having dual counter flow—a first counter flow configurationas between immediately adjacent regions of the first and second portions210, 212 of the flow path 202, and a second counter flow configurationdue to the interleaved winding of the adjacent first and second portions210, 212.

The dual counter flow configuration advantageously provides a lowtemperature difference between maximum and minimum temperatures of theshowerhead 114. For example, in an exemplary test model run by theinventors, a showerhead having a dual counter flow configuration asdescribed above and a conventional showerhead having a single counterflow configuration were heated uniformly and a coolant was provided inthe respective flow paths of the substrate supports to remove heat fromthe showerhead. Steady state measurements of temperature across theshowerheads yielded a temperature profile in the dual counter flowshowerhead that was more uniform than in the conventional showerhead. Inaddition, the temperature difference between respective maximum andminimum temperature measurements in each showerhead was advantageouslylower in the dual counter flow showerhead than in the conventionalshowerhead.

In some embodiments, and as depicted in FIG. 3, one or more channels 140may define two or more (two shown) flow paths 302, 306 coupled to oneanother via a common inlet 310 and outlet 308. The two or more flowpaths 302, 306 may be arranged in any configuration suitable to providesubstantially equal flow of the heat transfer fluid and to providecontrol over the temperature profile across the showerhead 114. Forexample, as depicted in FIG. 3, in some embodiments, the two or moreflow paths 302, 306 may begin at the inlet 310 and may be routed indifferent directions to cover different portions of the showerhead.

In some embodiments, the two or more flow paths 302, 306 may have asubstantially equivalent axial length, cross-sectional area, thusproviding substantially equal fluid conductance and residence time ofheat transfer fluid within each of the two or more flow paths 302, 306,thereby facilitating temperature uniformity between the two or more flowpaths 302, 306. By providing two or more flow paths 302, 306 the axiallength of each of the two or more flow paths 302, 306 may be decreased,as compared to a single flow path covering the same area, therebyproviding a shorter flow path for the heat transfer fluid. The shorterflow path for the heat transfer fluid decreases the change intemperature along the length of the two or more flow paths 302, 306between the inlet 310 and outlet 308 as compared to longer flow paths.In addition, by providing a shorter flow path for the heat transferfluid a pressure drop of the heat transfer fluid between the inlet 310and outlet 308 of two or more flow paths 302, 306 may also be decreased,allowing for an increased flow rate of heat transfer fluid, thus furtherdecreasing a change in temperature along the length of the two or moreflow paths 302, 306 between the inlet 310 and the outlet 308.

In some embodiments, and as depicted in FIG. 4, the one or more channels140 may define a plurality of flow paths (three shown) 408, 410, 412having a substantially equal fluid conductance and residence time. Insuch embodiments, each of the plurality of flow paths 408, 410, 412comprises an inlet 414, 418, 422 coupled to a first end 402, 404, 406and an outlet 416, 420, 424 coupled to a second end 417, 419, 421, thusproviding a flow path of heat transfer fluid from the inlet 414, 418,422 to the respective outlet 416, 420, 424. The plurality of flow paths408, 410, 412 may be coupled to a single heat transfer fluid source(described above with respect to FIG. 1). For example, a heat transferfluid outlet may be coupled to the plurality of outlets to provide anoutflow of heat transfer fluid from the plurality of outlets to the heattransfer fluid source. Alternatively, the plurality of flow paths may becoupled to a plurality of heat transfer fluid sources, wherein each ofthe plurality of flow paths 408, 410, 412 are respectively coupled to aseparate single heat transfer fluid source.

The plurality of flow paths 408, 410, 412 may be arranged in any mannersuitable to provide temperature uniformity across the substrate facingsurface of the showerhead 114. For example, in some embodiments, theplurality of flow paths 408, 410, 412 may be symmetrically positionedwithin the showerhead 114 to promote temperature uniformity. Byutilizing a plurality of flow paths 408, 410, 412 the axial length ofeach of the plurality of flow paths 408, 410, 412 may be shortened,which may advantageously allow for a decreased change in temperature ofthe heat transfer fluid along the flow paths 408, 410, 412 and thus anincreased control over temperature profile due to the principles (e.g.,residence time, fluid conductance, decreased pressure drop) discussedabove with respect to FIG. 3. In addition, by utilizing a plurality offlow paths 408, 410, 412 wherein each comprises an inlet 414, 418, 422,and outlet 416, 420, 424, such as depicted in FIG. 4, the total flowrate of heat transfer fluid throughout the showerhead may be increased,further facilitating a decreased temperature range of the showerheadduring use. In some embodiments, each of the plurality of flow paths maybe arranged to provide a counter flow within a given flow path. In someembodiments, each portion of the flow path adjacent to another flow pathcan be configured to provide counter flow. By providing each flow path,and optionally adjacent flow paths, in a counter flow configuration,temperature uniformity further improves.

In some embodiments, and as depicted in FIG. 5, the one or more channels140 may define a plurality of flow paths (six shown) 502, 504, 506, 508,510, 512 arranged in a plurality of zones 525, 526, 528. The pluralityof zones 525, 526, 528 may be arranged in any manner suitable to providecontrol of a temperature profile across the substrate-facing surface ofthe showerhead 114. For example, as shown in FIG. 5, the zones 525, 526,528 may have a substantially equivalent surface area and are arrangedsymmetrically across the showerhead 114. In such embodiments, each zone525, 526, 528 may comprise two or more of the plurality of flow pathscoupled to a common inlet and outlet. For example, as shown in FIG. 5,flow paths 502 and 504 are coupled to a common inlet 514 and a commonoutlet 516, flow paths 506 and 508 are coupled to inlet 518 and outlet520, and flow paths 510 and 512 are coupled to inlet 522 and outlet 524.In such embodiments, each of the plurality of flow paths 502, 504, 506,508, 510, 512 may comprise a substantially equivalent axial length andcross-sectional area, thus providing substantially equal fluidconductance and residence time of heat transfer fluid within each of theplurality of flow paths 502, 504, 506, 508, 510, 512, therebyfacilitating temperature uniformity in each of the zones 525, 526, 528.In some embodiments, the common inlets 514, 518, 522 may be coupled to aheat transfer fluid source (not shown) configured to provide the heattransfer fluid, as described above with respect to FIG. 1.Alternatively, in some embodiments, a separate heat transfer fluidsource may be coupled to each inlet 514, 518, 522 to provide a heattransfer fluid to each zone 525, 526, 528 individually.

By utilizing two or more of the plurality of flow paths 502, 504, 506,508, 510, 512 in each zone 525, 526, 528 the axial length of each of theplurality of flow paths 502, 504, 506, 508, 510, 512 may be shortened,which may advantageously allow for a decreased change in temperature ofthe heat transfer fluid along the flow paths 502, 504, 506, 508, 510,512 and thus an increased control in temperature uniformity due to theprinciples discussed above.

Alternatively, or in combination, in some embodiments and as depicted inFIG. 6, a plurality of flow paths (six shown) 606, 608, 610, 624, 626,628 may also be arranged in an inner zone 602 and an outer zone 604,wherein the outer zone 604 is disposed radially outward from the innerzone 602. Each of the inner zone 602 and outer zone 604 may comprise anynumber of the plurality of flow paths 606, 608, 610, 624, 626, 628 andmay be arranged in any manner suitable to facilitate temperatureuniformity across the substrate support 108. For example, as depicted inFIG. 6, the inner zone 602 may comprise a plurality (three shown) offlow paths 606, 608, 610, having a substantially equivalent axial lengthand fluid conductance, positioned symmetrically within the showerhead114. Each of the plurality of flow paths 606, 608, 610 comprises aninlet 612, 616, 620 and an outlet 614, 618, 622. The plurality of flowpaths 606, 608, 610 may be coupled to a common heat transfer fluidsource (not shown) configured to provide the heat transfer fluid, asdescribed above with respect to FIG. 1. Alternatively, in someembodiments, a separate heat transfer fluid source may be coupled toeach inlet 612, 616, 620 to provide a heat transfer fluid to each flowpath 606, 608, 610 individually.

In some embodiments, the inner zone 602 may comprise otherconfigurations of flow paths to facilitate temperature uniformity acrossthe substrate support 108. For example, in some embodiments, the innerzone 602 may further comprise a plurality of zones positionedsymmetrically, wherein each of the plurality of zones comprise more thanone flow path coupled to a common inlet and outlet, such as in theembodiments discussed above with respect to FIG. 5.

In some embodiments, the outer zone 604 may comprise a plurality (threeshown) of flow paths 624, 626, 628, wherein each of the plurality offlow paths 624, 626, 628 comprise an inlet 632, 636, 640 and outlet 630,634, 638. In some embodiments, each of the plurality of flow paths 624,626, 628 may be disposed adjacent to a corresponding flow path of theplurality of flow paths 606, 608, 610 of the inner zone 602. In suchembodiments the plurality (three shown) of flow paths 624, 626, 628 inthe outer zone 604 may provide a counter flow of heat transfer fluidwith respect to the adjacent flow path of the plurality of flow paths606, 608, 610 of the inner zone 602, allowing for a heat transfer from ahotter portion of the heat transfer fluid to a cooler portion of theheat transfer fluid, thus facilitating temperature uniformity betweenthe outer zone 604 and inner zone 602. In some embodiments, a barrier603 may be provided between the inner zone 602 and the outer zone 604 tofacilitate the independent control over the temperature in each zone,and temperature non-uniformity between the zones. In some embodiments,the barrier 603 may be an insulator such as an air gap, for example, ofabout 1 mm to about 10 mm wide.

In embodiments where multiple zones of heat transfer fluid flow pathsare provided, a valve (e.g., valve 139 depicted in FIG. 1) may becoupled to at least one, and in some embodiments, each of the pluralityof flow paths to control a flow rate of the heat transfer fluid flowingthrough one or more of the flow paths. A controller may be coupled toeach valve to control the operation thereof (e.g., controller 137depicted in FIG. 1). The each valve may be controlled to independentlyprovide a desired flow rate of heat transfer fluid through the flowpaths in each zone. As such, a flow rate in a given zone may beincreased or decreased with respect to the flow rate in any other zone.For example, a flow rate in an outer zone may be increased to removemore heat, or decreased to remove less heat, as desired to make athermal profile of a substrate-facing surface of the showerhead 114 moreuniform or controllably non-uniform (for example to control processresults in thermally dependent processes).

In some embodiments, and as depicted in FIG. 7, the showerhead 114 maycomprise two or more zones (four zones 702, 704, 706, 708 depicted inFIG. 7) arranged in a symmetrical pattern (a fourfold symmetricalpattern in FIG. 7), wherein each of the zones (e.g., 702, 704, 706, 708)includes at least one flow path (e.g., 726, 728, 730, 732) defining arecursive flow pattern in an azimuthal direction about the showerhead114. In such embodiments, each of the at least one flow paths maycomprise a substantially equivalent axial length and cross-sectionalarea, thus providing substantially equal fluid conductance and residencetime. The recursive flow pattern may advantageously provide asymmetrical flow path having a more uniform conductance. As such, thepressure and flow rate within each of the at least one flow paths may bemore uniform, resulting in an increased temperature uniformity acrossthe substrate-facing surface of the showerhead 114.

In some embodiments, each of the at least one flow paths may comprise aninlet (e.g., 710, 712, 714, 716) and an outlet (e.g., 718, 720, 722,724), wherein each of the inlets and outlets are coupled to a commoninlet (e.g., 734) and a common outlet (e.g., 736). In such embodiments,the distance between each inlet and the common inlet and the distancebetween each outlet and the common outlet are substantially equivalent,to facilitate a substantially equivalent flow rate of heat transferfluid, pressure difference, and residence time in each of the flowpaths. By providing a common inlet and common outlet in the mannerdescribed, each of the flow paths may be provided with heat transferfluid at the same rate, pressure, and the like. As such, the flow rateof the heat transfer fluid through each flow path may be substantiallyequal, thereby minimizing temperature non-uniformity associated withtransient flow of heat transfer fluid.

FIG. 8 depicts another partial cross sectional top view of a showerheadin accordance with some embodiments of the present invention. Asdepicted in FIG. 8, a showerhead 114 may include two flow channels 140.The flow channels may be inversely symmetric about an axis 802 thatpasses through a central axis of the showerhead 114 (e.g., a diameterfor circular showerheads). A first flow channel 804 may be providedbetween an inlet 806 and an outlet 808 disposed on a first half 810 ofthe showerhead 114. A second flow channel 812 may be provided between aninlet 814 and an outlet 816 disposed on a second half 818 of theshowerhead 114. The second flow channel 812 may have a similar oridentical shape as the first flow channel 804 and may be rotated 180degrees with respect to the first flow channel 804. In some embodiments,the inlet and outlet of each flow channel may be disposed proximate anouter edge, radially, of the flow channel. The flow channel may then berouted from the inlet towards the center of the showerhead and back fromthe center out towards the edge of the showerhead to the outlet. Eachflow channel 140 may be routed to provide a counter flow of the heattransfer fluid flowing therethrough during use to improve temperatureuniformity. By providing similarly or identically shaped flow channels,the temperature profile of the substrate facing side of the showerhead114 may additionally be made more azimuthally uniform. The dual-channeldesign reduces pressure differences between channels that facilitatesproviding a larger flow rate, hence providing further thermal profileuniformity improvement.

In each of the above embodiments, the number of zones and flow pathdirection may be varied to further facilitate temperature uniformityacross the faceplate of the showerhead.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof.

1. An apparatus for controlling thermal uniformity of a substrate-facingsurface of a showerhead, comprising: a showerhead having a substratefacing surface and one or more plenums for providing one or more processgases through a plurality of gas distribution holes formed through thesubstrate facing surface of the showerhead; and a plurality of flowpaths having a substantially equivalent fluid conductance disposedwithin the showerhead to flow a heat transfer fluid.
 2. The apparatus ofclaim 1, further comprising: a plurality of inlets, each respectivelycoupled to a first end of a respective one of the plurality of flowpaths; and a plurality of outlets, each respectively coupled to a secondend of a respective one the plurality of flow paths.
 3. The apparatus ofclaim 2, wherein the plurality of flow paths are symmetricallypositioned within the showerhead.
 4. The apparatus of claim 3, furthercomprising: a heat transfer fluid inlet coupled to the plurality ofinlets to provide in an inflow of heat transfer fluid to the pluralityof inlets; and a heat transfer fluid outlet coupled to the plurality ofoutlets to provide an outflow of heat transfer fluid from the pluralityof outlets.
 5. The apparatus of claim 3, wherein each of the pluralityof flow paths comprise a recursive symmetric pattern.
 6. The apparatusof claim 1, wherein the showerhead further comprises: a first platehaving the plurality of flow paths disposed at least partially therein;and a second plate disposed adjacent to the first plate, the secondplate having the one or more plenums at least partially formed therein.7. The apparatus of claim 1, wherein the plurality of flow paths arearranged in a plurality of zones having radial symmetry with respect toa central axis of the showerhead, wherein each of the plurality of zonescomprises at least two flow paths.
 8. The apparatus of claim 7, whereineach of the plurality of zones further comprises: an inlet coupled tothe at least two flow paths; and an outlet coupled to the at least twoflow paths.
 9. The apparatus of claim 8, wherein each of the at leasttwo flow paths are symmetrical with respect to one another.
 10. Theapparatus of claim 1, wherein each of the plurality of flow paths arecoupled to a common inlet and a common outlet.
 11. The apparatus ofclaim 1, further comprising a heat transfer fluid source configured toprovide the heat transfer fluid to the plurality of flow paths and tocontrol a temperature and a flow rate of the heat transfer fluid. 12.The apparatus of claim 1, wherein the showerhead further comprises: aninner portion having a first plurality of the plurality of flow pathsdisposed therein; and an outer portion having a second plurality of theplurality of flow paths disposed therein, the outer portion disposedradially outward of the inner portion with respect to a center point ofthe showerhead.
 13. The apparatus of claim 12, wherein each of theplurality of flow paths disposed in the outer portion of the showerheadis positioned adjacent to a respective each of the plurality of flowpaths disposed in the inner portion of the showerhead.
 14. The apparatusof claim 13, wherein each of the plurality of flow paths disposed in theouter portion of the showerhead is configured to provide a flow of heattransfer fluid in an opposite direction with respect to a direction offlow of heat transfer fluid of an adjacent one of the plurality of flowpaths disposed in the inner portion of the showerhead.
 15. The apparatusof claim 1, further comprising: at least one valve respectively coupledto the at plurality of flow paths to control a flow rate of the heattransfer fluid.
 16. The apparatus of claim 15, further comprising acontroller coupled to at least one valve to control the operationthereof.
 17. The apparatus of claim 1, wherein the showerhead furthercomprises at least one heating element to heat the showerhead.
 18. Theapparatus of claim 17, wherein the at least one heating elementcomprises a plurality of heating elements arranged in two or more zones.19. An apparatus for controlling thermal uniformity of asubstrate-facing surface of a showerhead, comprising: a showerheadhaving a substrate facing surface and one or more plenums for providingone or more process gases through a plurality of gas distribution holesformed through the substrate facing surface of the showerhead; and aflow path disposed within the showerhead and having an inlet and anoutlet to flow a heat transfer fluid through the flow path, wherein theflow path comprises a first portion and a second portion, each portionhaving a substantially equivalent axial length, wherein the firstportion is spaced about 2 mm to about 10 mm from the second portion, andwherein the first portion provides a flow of heat transfer fluid in adirection opposite a flow of heat transfer fluid of the second portion.20. An apparatus for controlling thermal uniformity of asubstrate-facing surface of a showerhead, comprising: a showerheadhaving a substrate facing surface and one or more plenums for providingone or more process gases through a plurality of gas distribution holesformed through the substrate facing surface of the showerhead; and afirst flow path and a second flow path disposed within the showerhead,each having an inlet and an outlet to flow a heat transfer fluid throughthe respective flow path, wherein each flow path has a substantiallyequivalent axial length, and wherein the first flow path and the secondflow path a inversely symmetrical about an axis that passes through acentral axis of the showerhead.